Yorkshire Water is the latest utilities company to be handed a large fine for environmental offences.
The company, which was fined £600,000, admitted one charge of causing a water discharge activity without an environmental permit.
Sewage had leaked from a storage tank at the Hinderwell Waste Water Treatment Works in July 2015, with the cause determined as poorly maintained storage tanks, with rust and holes.
Richard Bradley, prosecuting for the Environment Agency (EA), told of the impact on quality of the water in the affected area. The watercourse involved runs through a caravan park, and had a foul odour and discolouration.
Yorkshire Water initially blamed works at the nearby Potash Mine for the water discolouration, but four days after the spill it used dye testing to trace the source back to the treatment works.
The impact on wildlife was clear, with up to 100 dead fish seen. Tests showed the water had high levels of ammonia and low oxygen levels. The polluted water also affected the sea at Staithes Harbour, which at the time of the incident was designated as bathing water.
Three months after the incident, Yorkshire Water was still cleaning sewage from the water. The EA sent requests for a clean-up plan, but no reply was received.
Claire Campbell, environmental planning specialist at the EA, said: “This case demonstrates how important it is that water companies and wider industries maintain their equipment and facilities to a high standard to protect the environment.”
Yorkshire Water, in mitigation, informed the court of measures taken to prevent a similar incident happening, which included replacing the tank in question, the installation of a gully guard to contain any future spillages, and an alarm on the sludge tank.
The fine of £600,000 was in addition to legal costs of more than £28,000.
